Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Proposed Reaction Conundrum  (Read 2852 times)

0 Members and 1 Guest are viewing this topic.

nj_bartel

  • Sr. Member
  • *****
  • Mole Snacks: +76/-42
  • Offline Offline
  • Posts: 1491
Proposed Reaction Conundrum
« on: November 24, 2008, 04:45:23 PM »

A reaction I'm going to be running to determine the efficacy of a catalyst uses benzaldehyde and butyl acrylate.  The butyl acrylate is polymerization inhibited with hydroquinone monomethyl ether (MEHQ).  The MEHQ requires a 5-21% O2 by volume concentration to remain effective and avoid explosive polymerization.  However, the benzaldehyde undergoes oxidation with O2 to yield benzoic acid.  I'm unsure of the rate at which the benzaldehyde is oxidized, but the reaction duration will be 2+ days, and I have reason to believe from past experiments that there would be a significant amount of oxidation taking place in that time.  The problem is not that the benzoic acid would hurt the reaction - it would most likely serve to expedite it.  However, the if we're seeking to determine the efficacy of a proposed catalyst, the benzoic acid would be an x factor - we wouldn't be able to determine whether the benzoic acid was necessary for the reaction to proceed or not.  The reaction would be performed small-scale (~5g total) and neat - benzaldehyde, butyl acrylate, catalyst.

Any ideas on potential ways to run this?  Or any comments in general?
Logged

Mitch

  • Chemistry Editor
  • Administrator
  • Sr. Member
  • *
  • Mole Snacks: +355/-8
  • Offline Offline
  • Gender: Male
  • Posts: 5046
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re: Proposed Reaction Conundrum
« Reply #1 on: November 25, 2008, 05:36:10 AM »

You could setup an experiment to see how quickly the benzaldehyde turned to benzoic acid in air. That way you're not dealing with feelings but cold hard numbers.
Logged
Most Common Suggestions I Make on the Forums.
1. Always start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

nj_bartel

  • Sr. Member
  • *****
  • Mole Snacks: +76/-42
  • Offline Offline
  • Posts: 1491
Re: Proposed Reaction Conundrum
« Reply #2 on: November 25, 2008, 05:47:50 AM »

That would make data publishable, but it still doesn't solve the problem of desiring data with no benzoic acid (to speed the reaction, it would only need to be present in catalytic amounts).  Do you have any idea if antioxidants like lycopene work in this type of oxidation they same way they do in radical oxidations?  If lycopene would be effective, that'd be great - easily separated, unreactive.  It would be barely soluble in the reactants, but a stir bar would be running for the duration.
Logged

Mitch

  • Chemistry Editor
  • Administrator
  • Sr. Member
  • *
  • Mole Snacks: +355/-8
  • Offline Offline
  • Gender: Male
  • Posts: 5046
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re: Proposed Reaction Conundrum
« Reply #3 on: November 25, 2008, 09:21:20 AM »

I think your just going to have to perform a batch of these experiments small-scale and in triplicate, step back, and analyze the results. I would also recommend adding systematic amounts of benzoic acid to your reaction to see what effect that has on the yield. It just seems like you need more data about this potential problem. Nothing wrong with collecting data.
Logged
Most Common Suggestions I Make on the Forums.
1. Always start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

nj_bartel

  • Sr. Member
  • *****
  • Mole Snacks: +76/-42
  • Offline Offline
  • Posts: 1491
Re: Proposed Reaction Conundrum
« Reply #4 on: November 25, 2008, 11:03:37 AM »

Had a talk with a grad student today - MSDS only says explosive, but it's actually explosive in that it releases a fair amount of gas that can build up.  He said working under nitrogen would be fine, just to have it hook up to a bubbler.  Benzoic acid's going to be added if the reaction doesn't proceed without, at varying temperatures.
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.061 seconds with 24 queries.